ovl: update of dentry revalidate flags after copy up

After copy up, we may need to update d_flags if upper dentry is on a
remote fs and lower dentries are not.

Add helpers to allow incremental update of the revalidate flags.

Fixes: bccece1 ("ovl: allow remote upper")
Reviewed-by: Gao Xiang <[email protected]>
Signed-off-by: Amir Goldstein <[email protected]>
Signed-off-by: Miklos Szeredi <[email protected]>

Author: amir73il

fs/overlayfs/copy_up.c

@@ -575,6 +575,7 @@ static int ovl_link_up(struct ovl_copy_up_ctx *c)
 			/* Restore timestamps on parent (best effort) */
 			ovl_set_timestamps(ofs, upperdir, &c->pstat);
 			ovl_dentry_set_upper_alias(c->dentry);
+			ovl_dentry_update_reval(c->dentry, upper);
 		}
 	}
 	inode_unlock(udir);
@@ -894,6 +895,7 @@ static int ovl_do_copy_up(struct ovl_copy_up_ctx *c)
 		inode_unlock(udir);
 
 		ovl_dentry_set_upper_alias(c->dentry);
+		ovl_dentry_update_reval(c->dentry, ovl_dentry_upper(c->dentry));
 	}
 
 out:

fs/overlayfs/dir.c

@@ -269,8 +269,7 @@ static int ovl_instantiate(struct dentry *dentry, struct inode *inode,
 
 	ovl_dir_modified(dentry->d_parent, false);
 	ovl_dentry_set_upper_alias(dentry);
-	ovl_dentry_update_reval(dentry, newdentry,
-			DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
+	ovl_dentry_init_reval(dentry, newdentry);
 
 	if (!hardlink) {
 		/*

fs/overlayfs/export.c

@@ -326,8 +326,7 @@ static struct dentry *ovl_obtain_alias(struct super_block *sb,
 	if (upper_alias)
 		ovl_dentry_set_upper_alias(dentry);
 
-	ovl_dentry_update_reval(dentry, upper,
-			DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
+	ovl_dentry_init_reval(dentry, upper);
 
 	return d_instantiate_anon(dentry, inode);
 

fs/overlayfs/namei.c

@@ -1122,8 +1122,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 			ovl_set_flag(OVL_UPPERDATA, inode);
 	}
 
-	ovl_dentry_update_reval(dentry, upperdentry,
-			DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
+	ovl_dentry_init_reval(dentry, upperdentry);
 
 	revert_creds(old_cred);
 	if (origin_path) {

fs/overlayfs/overlayfs.h

@@ -375,8 +375,10 @@ bool ovl_index_all(struct super_block *sb);
 bool ovl_verify_lower(struct super_block *sb);
 struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
 bool ovl_dentry_remote(struct dentry *dentry);
-void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *upperdentry,
-			     unsigned int mask);
+void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *realdentry);
+void ovl_dentry_init_reval(struct dentry *dentry, struct dentry *upperdentry);
+void ovl_dentry_init_flags(struct dentry *dentry, struct dentry *upperdentry,
+			   unsigned int mask);
 bool ovl_dentry_weird(struct dentry *dentry);
 enum ovl_path_type ovl_path_type(struct dentry *dentry);
 void ovl_path_upper(struct dentry *dentry, struct path *path);

fs/overlayfs/super.c

@@ -1877,7 +1877,7 @@ static struct dentry *ovl_get_root(struct super_block *sb,
 	ovl_dentry_set_flag(OVL_E_CONNECTED, root);
 	ovl_set_upperdata(d_inode(root));
 	ovl_inode_init(d_inode(root), &oip, ino, fsid);
-	ovl_dentry_update_reval(root, upperdentry, DCACHE_OP_WEAK_REVALIDATE);
+	ovl_dentry_init_flags(root, upperdentry, DCACHE_OP_WEAK_REVALIDATE);
 
 	return root;
 }

fs/overlayfs/util.c

@@ -94,14 +94,30 @@ struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
 	return oe;
 }
 
+#define OVL_D_REVALIDATE (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE)
+
 bool ovl_dentry_remote(struct dentry *dentry)
 {
-	return dentry->d_flags &
-		(DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
+	return dentry->d_flags & OVL_D_REVALIDATE;
+}
+
+void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *realdentry)
+{
+	if (!ovl_dentry_remote(realdentry))
+		return;
+
+	spin_lock(&dentry->d_lock);
+	dentry->d_flags |= realdentry->d_flags & OVL_D_REVALIDATE;
+	spin_unlock(&dentry->d_lock);
+}
+
+void ovl_dentry_init_reval(struct dentry *dentry, struct dentry *upperdentry)
+{
+	return ovl_dentry_init_flags(dentry, upperdentry, OVL_D_REVALIDATE);
 }
 
-void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *upperdentry,
-			     unsigned int mask)
+void ovl_dentry_init_flags(struct dentry *dentry, struct dentry *upperdentry,
+			   unsigned int mask)
 {
 	struct ovl_entry *oe = OVL_E(dentry);
 	unsigned int i, flags = 0;